(1) Field of the Invention
This invention relates to a heat-sensitive and heat transfer recording sheet with pressure sensitivity.
(2) Description of the Prior Art
In recent years, in addition to the conventional heat-sensitive recording method using a thermal recording equipment such as a thermal printer, a thermal facsimile or the like, there has been put into practical use a heat transfer recording method having advantages such as retainability after recording, indelibility, solvent resistance and the like. In the latter method, a heat transfer recording sheet consisting of a base sheet and a heat-meltable ink layer coated on one side of the base sheet is superimposed on a plain paper so that the ink layer side of the recording sheet faces the plain paper; then, heat is applied onto the heat transfer recording sheet by a thermal head of a thermal facsimile or the like; thereby the ink of the heat transfer recording sheet is transferred onto the plain paper and thus recording is made. Heat transfer recording in a single color (e.g. black color) is already in practical use.
There is also a heat-sensitive and heat transfer recording sheet obtained by providing a heat-sensitive color-developing layer on the non-coated side of a heat transfer recording sheet. This heat-sensitive and heat transfer recording sheet enables multiple recording.
With respect to the heat transfer recording sheet, it has recently been desired that the sheet also have pressure sensitivity in order to enable, whenever necessary, pressure printing by a method such as hand writing, typewriting or the like. Hence, a heat-meltable ink also having pressure sensitivity is being studied.
However, having pressure sensitivity means being liable to cause staining during handling.
In the heat-sensitive and heat transfer recording sheet obtained by providing a heat-sensitive color-developing layer on the non-coated side of a heat transfer recording sheet, the heat-meltable ink of the heat transfer recording layer contains a color dye or color pigment and hence the heat transfer recording layer has a color. This color is seen through even at the heat-sensitive color-developing layer, and this "seen through" problem is not good from the appearance standpoint and reduces the readability of printed image. Therefore, improvements are under way.
For example, in Japanese Patent Application Kokai (Laid-open) No. 78793/1983, there is disclosed a heat recording copying sheet comprising a base sheet, a heat-sensitive color-developing layer provided on one side of the base sheet and a heat-meltable color ink layer provided on the other side of the base sheet. In this copying sheet, in order to prevent the "seen through" problem due to the heat-meltable color ink, a vapor deposition layer is provided on the base sheet before the heat-sensitive color-developing layer is provided. This makes the production of the copying sheet more complicated and incurs a higher production cost.